SYDNEY: Disgraced Cardinal George Pell lodged an appeal against his child sex abuse convictions in Australia's High Court on Tuesday, in a last-ditch effort to clear his name.

Pell filed his application for leave to appeal just one day before the 28-day lodgement window closed, a court official in Canberra told AFP.

It is the final avenue for the 78-year-old, who is serving a six-year sentence for sexually assaulting two choirboys in a Melbourne cathedral in the 1990s, to get out of jail.

But there is no guarantee that the High Court will agree to consider Pell's case.

Australia's most senior judges will now deliberate on whether to allow the appeal to proceed, a process that could take months.

The former Vatican treasurer, who once helped elect popes, last month lost his appeal in Victoria state's Court of Appeal in a landmark decision that saw the judges split in a 2-1 verdict.

That division - which saw two judges back the jury's verdict and the dissenting judge sides with Pell - is at the forefront of his latest bid to overturn the convictions.

The case pitted the most senior convicted Catholic child molester against a former choirboy now in his 30s, who two of the judges found to be "very compelling" and someone who "was clearly not a liar, was not a fantasist and was a witness of truth".

The third judge, however, found the victim's account "contained discrepancies" and there was a "significant possibility" Pell did not commit the offences.

Court documents show his legal team are mounting two grounds of appeal, with the key argument being the majority judges applied an "erroneous judicial method" in "upholding with the jury's verdict".

The second contends there was not enough time for Pell to have molested the boys in the priests' sacristy during a 5-6 minute period after Sunday Mass ended and the area became a "hive of activity".

The High Court receives about 500 appeal applications each year and "rarely" takes them on, with about 35 being heard each year, University of Melbourne legal expert Jeremy Gans told AFP.

But Gans said the unique nature of the case - and the fact that it is "the most high profile in Victoria's history" - could convince the judges to hear the case.

Pell and his supporters have staunchly maintained he did not commit the crimes, which came to light after one of the victims went to police when the other died of a drug overdose in 2014.

During Pell's trial under a court-ordered veil of secrecy, the Vatican gradually removed him from top Church bodies with little explanation.

Shortly after his conviction, Pell was removed from the so-called C9 Council of Cardinals that are effectively the Pope's cabinet and inner circle of advisers.

The Vatican later dropped him as the church's finance chief but revealed last month it would avoid launching an investigation into his conduct until after all legal avenues are exhausted.

A number of senior Australian Catholics are standing by Pell, including the Archbishop of Melbourne, who reiterated his belief in the cardinal last month. (THE NEW INDIAN EXPRESS)